Currently monitoring of skier/skiing performance relies on few techniques, such as: skier feelings, instructor/coach observations, etc, and some empirical factors, such as: time measurements, post run video analysis, while the safety and comfort depends on decades old ski binding technology, incremental progress in materials and manufacturing technology.
Some analytical methods for data collection during the development phase of the ski equipment are in use today, however, most of those techniques are not practical for the every day training of professional or recreational skier, as they require bulky equipment and require large team of highly skilled technicians to operate.
It is well known that the safety of skiing depends predominantly on ski bindings. Currently, binding safety is defined by the stiffness of it's spring(s) used to hold/release ski boot, which is adjusted according to the presumed capability of the user and the user weight. This basic principle of ski binding didn't changed in past 40 years (also many incremental improvements, such as: multi-pivots/springs were added), and perform satisfactory most of the time—when the speeds are modest, the spring pre-set torque was below the critical level and the user is physically fit, the fundamental problem—relying on intuition for setting the spring strength and fact that in almost all cases, only one of the binding, the one experiencing excessive force, will release. This is mainly to the fact that the forces applied to both skis and/or skis trajectory are not the same. In effect, while one ski is released the other, the other is still attached to the user causing serious injuries during a fall.
The comfort and safety of skiing is also affected by excessive ski vibration. Such vibrations are an effect of the moments applied to the ski edge by skier body position in relation to ski slope when the ski turns, especially on a hard icy snow or moguls. Since part of skiing experience is related to turns, manufacturers introduced skis with strong sideline curvature—broader tip and tail and narrow center, and high flexibility. Unfortunately, such design leads to large vibration amplitudes, so skis are manufactured with different stiffness factor to balance the needs and experience of broad range of skiing enthusiasts, from beginners to professionals. In effect, soft and highly flexible skis, targeting average expertise levels and/or soft snow have tendencies to vibrate excessively at high speeds or in tight turns or hard or icy snow, while less flexible or stiffer skis, targeted for experts are difficult to control by an average skilled user. However, all skis, regardless of their design parameters will vibrate in turns does loosing the edge contact with the snow making edge control difficult and increases discomfort and decreases safety and performance.
Depending on the speed and snow condition, ski vibrates at several bending and torsional frequencies with the amplitudes of such vibration dependent on ski construction—stiff and hard ski may have lower amplitudes at some frequencies but are difficult to control by an average user, while soft ski may be easy to control but have higher vibration amplitudes. In general, the ski bending frequencies are between 10 Hz and 100 Hz, while the torsional frequencies are in the range of 100 Hz to 150 Hz.
For several decades designers try different materials, manufacturing techniques and vibration damping schemes to somehow minimize its negative effect. As the ski vibrates predominantly at the front and the tail quarters of its length, various damping materials and structures were added to the front, tip and tail of the ski.
However, adding large amount of damping does not solve this problem while making ski less responsive and slow. It is well know that ski vibrates over relatively wide range of frequencies, and while dampening materials or dampening viscous structures are effective to damp particular frequency, such structures are not efficient in damping wide range of frequencies, and sometime even counterproductive. Ceramic piezoelectric structures were proposed to provide active dampeners, however, since only small amount of strain—as low as 1%, is usable to provide the control signal, they proved to be difficult to control and unstable or require “pre-tension” of the piezoelectric material in proportion to the expected bending forces in order to produce reference signal, and as such not compatible with ski manufacturing technologies.
As the current monitoring systems are not practical for every day use, not only the analysis of the skier run is relegate to post run subjective interpretation, but more significantly the safety of the skier (such as the response of the ski bindings) is left virtually unchanged for the past thirty years, thus also the number of recreational skiers increased, their safety and experience is not improved.
In recent years, the use of mobile devices and, in particular, cellular telephones has proliferated. Today, cellular phone besides providing basic communication over cellular network is equipped with various input/output capabilities, such as wireless PAN (Personal Area Network), and provides significant computing resources. When such computing resources communicate with the remote sensors, such as MEMS accelerometers, magnetometers, gyroscopes, pressure sensors, actuators the resulting system can provide various sport analytical tools for monitoring of v skiing.
By coupling MEMS accelerometers and actuators embedded in the ski equipment with an analysis application residing in the user smart-phone, one can provide tool analyzing forces experienced by the user and increase in safety and comfort of skiing. Furthermore, using the smart-phone connectivity to the wireless cellular network, a real-time feedback to the remote location may be provided to add in ski testing or training. System described in this invention can operate using any of wireless technology such as: cdma2000, UMTS, WiMax, LTE. LTE-A, etc.